Role of Cholesterol in the Regulation of Hydrogen Sulfide Signaling within the Vascular Endothelium.

H 2 S is a gaseous signaling molecule enzymatically produced in mammals and H 2 S-producing enzymes are expressed throughout the vascular wall. We previously reported that H 2 S-induced vasodilation is mediated through transient receptor potential cation channel subfamily V member 4 (TRPV4) and large conductance (BK Ca ) potassium channels; however, regulators of this pathway have not been defined. Previous reports have shown that membrane cholesterol limits activity of TRPV4 and BK Ca potassium channels. The current study examined the ability of endothelial cell (EC) plasma membrane (PM) cholesterol to regulate H 2 S-induced vasodilation. We hypothesized that EC PM cholesterol hinders H 2 S-mediated vasodilation in large mesenteric arteries. In pressurized, U46619 pre-constricted mesenteric arteries, decreasing EC PM cholesterol in large arteries using methyl-β-cyclodextrin (MBCD, 100 µM) increased H 2 S-induced dilation (NaHS 10, 100 µM) but MBCD treatment had no effect in small arteries. Enface fluorescence showed EC PM cholesterol content is higher in large mesenteric arteries than in smaller arteries. The NaHS-induced vasodilation following MBCD treatment in large arteries was blocked by TRPV4 and BK Ca channel inhibitors (GSK219384A, 300 nM and iberiotoxin, 100 nM, respectively). Immunohistochemistry of mesenteric artery cross-sections show that TRPV4 and BK Ca are both present in EC of large and small arteries. Cholesterol supplementation into EC PM of small arteries abolished NaHS-induced vasodilation but the cholesterol enantiomer, epicholesterol, had no effect. Proximity ligation assay studies did not show a correlation between EC PM cholesterol content and the association of TRPV4 and BK. Collectively, these results demonstrate that EC PM cholesterol limits H 2 S-induced vasodilation through effects on EC TRPV4 and BK Ca channels.